UnitSphericalRepresentation¶
-
class
astropy.coordinates.
UnitSphericalRepresentation
(lon, lat=None, differentials=None, copy=True)[source]¶ Bases:
astropy.coordinates.BaseRepresentation
Representation of points on a unit sphere.
- Parameters
- lon, lat
Quantity
or str The longitude and latitude of the point(s), in angular units. The latitude should be between -90 and 90 degrees, and the longitude will be wrapped to an angle between 0 and 360 degrees. These can also be instances of
Angle
,Longitude
, orLatitude
.- differentialsdict,
BaseDifferential
, optional Any differential classes that should be associated with this representation. The input must either be a single
BaseDifferential
instance (see_compatible_differentials
for valid types), or a dictionary of of differential instances with keys set to a string representation of the SI unit with which the differential (derivative) is taken. For example, for a velocity differential on a positional representation, the key would be's'
for seconds, indicating that the derivative is a time derivative.- copybool, optional
If
True
(default), arrays will be copied. IfFalse
, arrays will be references, though possibly broadcast to ensure matching shapes.
- lon, lat
Attributes Summary
The latitude of the point(s).
The longitude of the point(s).
Methods Summary
cross
(self, other)Cross product of two representations.
from_cartesian
(cart)Converts 3D rectangular cartesian coordinates to spherical polar coordinates.
mean
(self, *args, **kwargs)Vector mean.
norm
(self)Vector norm.
represent_as
(self, other_class[, …])Convert coordinates to another representation.
scale_factors
(self[, omit_coslat])Scale factors for each component’s direction.
sum
(self, *args, **kwargs)Vector sum.
to_cartesian
(self)Converts spherical polar coordinates to 3D rectangular cartesian coordinates.
unit_vectors
(self)Cartesian unit vectors in the direction of each component.
Attributes Documentation
-
attr_classes
= {'lat': <class 'astropy.coordinates.angles.Latitude'>, 'lon': <class 'astropy.coordinates.angles.Longitude'>}¶
-
lat
¶ The latitude of the point(s).
-
lon
¶ The longitude of the point(s).
Methods Documentation
-
cross
(self, other)[source]¶ Cross product of two representations.
The calculation is done by converting both
self
andother
toCartesianRepresentation
, and converting the result back toSphericalRepresentation
.- Parameters
- otherrepresentation
The representation to take the cross product with.
- Returns
- cross_product
SphericalRepresentation
With vectors perpendicular to both
self
andother
.
- cross_product
-
classmethod
from_cartesian
(cart)[source]¶ Converts 3D rectangular cartesian coordinates to spherical polar coordinates.
-
mean
(self, *args, **kwargs)[source]¶ Vector mean.
The representation is converted to cartesian, the means of the x, y, and z components are calculated, and the result is converted to a
SphericalRepresentation
.Refer to
mean
for full documentation of the arguments, noting thataxis
is the entry in theshape
of the representation, and that theout
argument cannot be used.
-
norm
(self)[source]¶ Vector norm.
The norm is the standard Frobenius norm, i.e., the square root of the sum of the squares of all components with non-angular units, which is always unity for vectors on the unit sphere.
- Returns
- norm
Quantity
Dimensionless ones, with the same shape as the representation.
- norm
-
represent_as
(self, other_class, differential_class=None)[source]¶ Convert coordinates to another representation.
If the instance is of the requested class, it is returned unmodified. By default, conversion is done via cartesian coordinates.
- Parameters
- other_class
BaseRepresentation
subclass The type of representation to turn the coordinates into.
- differential_classdict of
BaseDifferential
, optional Classes in which the differentials should be represented. Can be a single class if only a single differential is attached, otherwise it should be a
dict
keyed by the same keys as the differentials.
- other_class
-
scale_factors
(self, omit_coslat=False)[source]¶ Scale factors for each component’s direction.
Given unit vectors \(\hat{e}_c\) and scale factors \(f_c\), a change in one component of \(\delta c\) corresponds to a change in representation of \(\delta c \times f_c \times \hat{e}_c\).
- Returns
- scale_factorsdict of
Quantity
The keys are the component names.
- scale_factorsdict of
-
sum
(self, *args, **kwargs)[source]¶ Vector sum.
The representation is converted to cartesian, the sums of the x, y, and z components are calculated, and the result is converted to a
SphericalRepresentation
.Refer to
sum
for full documentation of the arguments, noting thataxis
is the entry in theshape
of the representation, and that theout
argument cannot be used.
-
to_cartesian
(self)[source]¶ Converts spherical polar coordinates to 3D rectangular cartesian coordinates.
-
unit_vectors
(self)[source]¶ Cartesian unit vectors in the direction of each component.
Given unit vectors \(\hat{e}_c\) and scale factors \(f_c\), a change in one component of \(\delta c\) corresponds to a change in representation of \(\delta c \times f_c \times \hat{e}_c\).
- Returns
- unit_vectorsdict of
CartesianRepresentation
The keys are the component names.
- unit_vectorsdict of